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Only a few previous works investigated the involvement of Chlamydia pneumoniae (Chlamydophila pneumoniae) in arterial calcification. The present study investigated a possible association between C. pneumoniae and medial calcification. Carotid artery segments obtained by endarterectomy from 60 patients were examined by PCR and immunohistochemistry to identify the presence of C. pneumoniae. Arterial specimens showing double-positive (n = 17), double-negative (n = 22), and single-positive results (n = 21) were further analyzed by a combination of histology, immunohistochemistry, and electron microscopy. Medial calcification occurred in 10 of 17 (58.8%) C. pneumoniae double-positive arterial specimens, but no medial calcification was observed in any of 22 C. pneumoniae double-negative arterial specimens. Electron microscopy indicated C. pneumoniae in smooth muscle cells (SMCs) in foci of medial calcification. Medial SMCs showing damage to the cytoplasm and basement membrane contained the structures with the appearance of elementary, reticulate, and aberrant bodies of C. pneumoniae. The presence of C. pneumoniae in SMCs was confirmed by electron-microscopic immunocytochemistry. In the extracellular matrix, calcification was observed in C. pneumoniae aberrant bodies that exited the SMCs. The findings offer a new hypothesis of arterial calcification: they suggest that C. pneumoniae infection of medial SMCs may be associated with the pathophysiological events of arteriosclerotic calcification of the tunica media. arteriosclerosis: smooth muscle cells

Since graduated compression stockings (GCS) reduce the risk of deep venous thrombosis (DVT) in both hospital and ambulant patients, we checked the compressive efficiency of 20−30 mmHg GCS in the standing position. In 30 volunteers (17 normal legs, 13 varicose legs), duplex ultrasound was used to measure the internal diameters of the long saphenous vein, posterior tibial veins, peroneal veins, and soleal veins in the lying and standing position and with and without 20−30 mmHg GCS. Graduated compression stockings effectively compressed both superficial and deep veins in supine individuals but not the superficial or the deep veins when standing. In the varicose leg, the stockings did not compress the long saphenous vein at the mid-calf level even when supine. In the varicose leg the long saphenous vein was constricted at the upper band of the stocking, which might explain why superficial venous thrombosis is more common when compression stockings are worn. In the standing position, GCS did not compress the deep or superficial veins of the calf. [ABSTRACT FROM AUTHOR]

Objective: Dendritic cells (DCs) accumulate in atherosclerotic lesions but their characteristics and their role in atherogenesis are poorly understood. C1q, an element of the first component of complement, is expressed by interdigitating dendritic cells and follicular dendritic cells in the spleen. It has been suggested that C1q is involved in capturing immune complexes in the lymphoid tissue. Immune complexes are also detected in atherosclerotic lesions. The present study investigated whether C1q is expressed by DCs in the arterial wall. Because DCs accumulating within atherosclerotic lesions might originate from monocytes that infiltrate the intima from very early stages of atherosclerosis, C1q expression was also examined in monocyte-derived DCs in vitro. Methods: Specimens of the aorta, carotid, mammary, popliteal and tibial arteries were obtained during operation. Expression of C1q in the arterial wall was studied by immunohistochemistry. The nature of cells expressing C1q was studied in sections double stained with antibodies to C1q and cell type specific markers including CD1a and S-100 (for identification of DCs), CD68 (macrophages), CD3 (T-cells), von Willebrand factor (endothelial cells), and smooth muscle α-actin (smooth muscle cells). In vitro, DCs were differentiated from human peripheral blood monocytes using GM-CSF and IL-4. Peripheral blood monocytes were differentiated to macrophages using M-CSF. The expression of C1q in monocytes and in vitro monocyte-derived DCs and macrophages was determined by RT-PCR, Western blotting, immunofluorescence microscopy and flow cytometry. Results: In all the arterial specimens studied, DCs expressing C1q were detected. C1q was also found in macrophages, macrophage foam cells and in neovascular endothelial cells in atherosclerotic lesions, but no C1q expression was detected in T-cells and smooth muscle cells. In vitro analysis demonstrated that monocyte-derived DCs and macrophages express C1q but no C1q was detected in monocytes. Conclusion: C1q is expressed by DCs residing in the arterial wall as well as by monocyte-derived DCs in vitro. Expression of C1q occurs during differentiation of monocytes to DCs and macrophages and might be important in binding and trapping immune complexes in atherosclerotic lesions. [Copyright &y& Elsevier]

Objective: The present work aimed to investigate how the Ca2+-dependent cell adhesion molecule vascular endothelial (VE)-cadherin might be involved in atherogenesis. Methods: Specimens of human carotid artery and aorta were obtained at operation. An immunohistochemical approach using cell-type specific antibodies examined how VE-cadherin expression in areas of neovascularisation related to the accumulation of immunocompetent and inflammatory cells within atherosclerotic plaque. Electron microscopy was used to examine the structural characteristics of neovessels and the cell composition in the surrounding intimal matrix. Results: In all the non-atherosclerotic aortic segments, VE-cadherin expression was observed only in the adventitia and the outer third of the media. Within the atherosclerotic arterial segments, VE-cadherin was expressed in all layers of the arterial wall including the intima where VE-cadherin was expressed by endothelial cells in areas of neovascularisation. In some neovessels, loss of VE-cadherin expression was associated with increased focal accumulation of T-cells, macrophages and dendritic cells. Electron-microscopic examination demonstrated varying degrees of endothelial continuity in the intimal neovessels. Within those neovessels which were surrounded by a large number of immunocompetent and inflammatory cells, some inter-endothelial cell contacts were open allowing the penetration of blood cells through patent intercellular zones. Conclusions: VE-cadherin is expressed in atherosclerotic lesions by endothelial cells associated with neovascularisation. Downregulation of VE-cadherin expression within some intimal neovessels is accompanied by increased entry of immunocompetent cells into the intimal matrix surrounding areas of neovascularisation which suggests that disorganising endothelial cell-to-cell interactions within neovessels is significant in atherogenesis. [ABSTRACT FROM PUBLISHER]

Objective: Various cell adhesion molecules are expressed in atherogenesis and the significance of their involvement in atherosclerotic lesion formation is well appreciated. In the present work, we examined whether the Ca2+-dependent cell adhesion molecule E-cadherin is also involved in atherogenesis. Methods: Specimens of carotid artery and aorta were obtained at operation. Expression of E-cadherin was studied by an immunohistochemical method. The nature of E-cadherin-expressing cells was examined by comparative analysis of consecutive sections and by a double immunostaining procedure. An immunohistochemical approach was also applied to examine how the accumulation of oxidised low density lipoproteins (LDL) by intimal cells is associated with E-cadherin expression. Results: No E-cadherin+ cells were found in normal non-atherosclerotic intima but E-cadherin+ cells were present in 96% of the atherosclerotic lesions. In atherosclerotic intima, E-cadherin was expressed by intimal cells showing varying degrees of transformation into foam cells. These E-cadherin+ cells also contained oxidised LDL in their cytoplasm. Differing numbers of CD68+ foam cells (15% to 60%) expressed E-cadherin but all the CD68+ macrophages without signs of transformation into foam cells were negative for E-cadherin. Neither smooth muscle cells nor foam cells of smooth muscle cell origin (smooth muscle alpha-actin+) were found to be positive for E-cadherin. T-cells (CD3+) and endothelial cells (von Willebrand factor+) were also negative for E-cadherin. Only a few vascular dendritic cells (S-100+) expressed E-cadherin and their expression was weak. We also found that a large proportion (40% to 85%) of E-cadherin+ cells did not stain with any cell-type specific markers. Conclusions: The finding that E-cadherin is expressed in atherosclerotic lesions expands our knowledge of cell adhesion molecules involved in atherogenesis. That E-cadherin is expressed in intimal cells transforming into foam cells suggests that lipid accumulation might be associated with the alteration and reorganisation of cell-to-cell interactions in atherogenesis. The present observations might assist in understanding the mechanisms associated with intracellular lipid accumulation. [ABSTRACT FROM PUBLISHER]

Objective: We previously demonstrated that vascular dendritic cells (VDCs) are present in the intima of large arteries and that their numbers are increased in atherosclerotic lesions. This study was undertaken to determine whether VDCs are involved in immune-mediated reactions in atherogenesis. Methods: Specimens of carotid artery and aorta were obtained at operation. VDCs were identified with anti-CD1a or with S-100. Co-localisation of VDCs with different intimal cells, including T-cells and macrophages, was studied using a double immunostaining procedure. In areas where the co-localising cells were detected, the peculiarities of expression of HLA-DR, ICAM-1, VCAM-1 were examined. Results: In all the atherosclerotic plaques, VDCs were seen in contact with T-cells, but these co-localising cells were irregularly distributed and were mainly found in zones of neovascularisation containing inflammatory infiltrates. In other areas, T-cell/VDC co-localisation was rarely detected but VDCs were often found in contact with macrophages. VDCs were detected also in the media beneath atherosclerotic lesions and in the adventitia, where they were mostly around vasa vasorum, especially in areas exhibiting signs of acute inflammation. In these areas VDCs expressed ICAM-1, VCAM-1 and were in contact with T-cells. In both plaques and in the adventitia, the areas with co-localising VDCs and T-cells corresponded to the areas with HLA-DR expression. Conclusions: The results suggest that VDCs are involved in T-cell activation in atherogenesis. There are two regions within the arterial wall where VDC/T-cell co-localisation mostly occurs, namely, in zones of neovascularisation containing inflammatory infiltrates located within atherosclerotic lesions, and in areas with inflammatory infiltrates around vasa vasorum in the adventitia. Possibly, some intimal VDCs migrate through the media and adventitia to adjacent lymph nodes where they present atherosclerosis associated antigens. We also speculate that VDC/macrophage contacts are essential in processing immune information in atherogenesis. [ABSTRACT FROM PUBLISHER]